Sensitivity of subregional distribution of socioeconomic conditions to the global assessment of water scarcity

Water availability per capita is among the most fundamental water-scarcity indicators used extensively in global grid-based water resources assessments. Recently, it has extended to include the economic aspect, a proxy of the capability for water management which we applied globally under socioeconomic-climate scenarios using gridded population and economic conditions. We found that population and economic projection choices significantly influence the global water scarcity assessment, particularly the assumption of urban concentrated and dispersed population. Using multiple socioeconomic-climate scenarios, global climate models, and two gridded population datasets, capturing extremities, we show that the water-scarce population ranges from 0.32-665 million in the future. Uncertainties in the socioeconomic-climate scenarios and global climate models are 6.58-489 million and 0.03-248 million, respectively. The population distribution has a similar impact, with an uncertainty of 169.1-338 million. These results highlight the importance of the subregional distribution of socioeconomic factors for future global environment prediction. Variation in global water scarcity is strongly dependent on the spatial distribution of population and economic conditions, according to a quantitative assessment of combined physical and economic water scarcity under multiple future emissions scenarios.

Automated summary

Population and economic factors have a significant impact on global water scarcity assessment. The uncertainty of multiple factors leads to a wide range of future water-scarce population, and population distribution also has a significant influence on global water scarcity.